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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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Aircraft equipment problem. Loose HF connector. Electromagnetic energy disconnected autoplt and automatic throttles.
| Attributes | |
| ACN | 314850 |
| Time | |
| Date | 199509 |
| Day | Sat |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : czqx |
| State Reference | NF |
| Altitude | msl bound lower : 36600 msl bound upper : 37000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : czqx |
| Operator | common carrier : air carrier |
| Make Model Name | DC-10 30 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other |
| Flight Phase | cruise other |
| Route In Use | enroute airway : czqx |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp pilot : commercial pilot : flight engineer pilot : instrument |
| Experience | flight time last 90 days : 20 flight time total : 4500 flight time type : 20 |
| ASRS Report | 314850 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : returned to intended course or assigned course |
| Consequence | Other Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
At 49N/50W we were at waypoint passage. This is where I keyed (tuned HF1 radio) HF1 radio to give a position report to gander oceanic control. The instant I keyed the microphone, it kicked off the autoplt and autothrottles. Since we were in a turn (over waypoint to next waypoint) and by time the captain saw what had happened, we'd lost 200 ft. By time maneuver to regain altitude was complete, we had lost a total of 350 ft down to 36650 ft. We were back to FL370 very quickly within 1 min. As it turned out (from maintenance) a loose HF electrical connector had caused our problems of autoplt and autothrottles disconnecting. High pwred HF radios do this, they told us. We actually discovered the cause of the disconnects later in the flight. Every time I gave a position report (keyed the microphone), we lost either autoplt and/or autothrottles.
Original NASA ASRS Text
Title: ACFT EQUIP PROB. LOOSE HF CONNECTOR. ELECTROMAGNETIC ENERGY DISCONNECTED AUTOPLT AND AUTO THROTTLES.
Narrative: AT 49N/50W WE WERE AT WAYPOINT PASSAGE. THIS IS WHERE I KEYED (TUNED HF1 RADIO) HF1 RADIO TO GIVE A POS RPT TO GANDER OCEANIC CTL. THE INSTANT I KEYED THE MIKE, IT KICKED OFF THE AUTOPLT AND AUTOTHROTTLES. SINCE WE WERE IN A TURN (OVER WAYPOINT TO NEXT WAYPOINT) AND BY TIME THE CAPT SAW WHAT HAD HAPPENED, WE'D LOST 200 FT. BY TIME MANEUVER TO REGAIN ALT WAS COMPLETE, WE HAD LOST A TOTAL OF 350 FT DOWN TO 36650 FT. WE WERE BACK TO FL370 VERY QUICKLY WITHIN 1 MIN. AS IT TURNED OUT (FROM MAINT) A LOOSE HF ELECTRICAL CONNECTOR HAD CAUSED OUR PROBS OF AUTOPLT AND AUTOTHROTTLES DISCONNECTING. HIGH PWRED HF RADIOS DO THIS, THEY TOLD US. WE ACTUALLY DISCOVERED THE CAUSE OF THE DISCONNECTS LATER IN THE FLT. EVERY TIME I GAVE A POS RPT (KEYED THE MIKE), WE LOST EITHER AUTOPLT AND/OR AUTOTHROTTLES.
Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.